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Linux KernelOperating system · Linux

CVE-2026-53073

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 5.5 / 5.10.258 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_ldisc: Clear HCI_UART_PROTO_INIT on error When hci_register_dev() fails in hci_uart_register_dev() HCI_UART_PROTO_INIT is not cleared before calling hu->proto->close(hu) and setting hu->hdev to NULL. This means incoming UART data will reach the protocol-specific recv handler in hci_uart_tty_receive() after resources are freed. Clear HCI_UART_PROTO_INIT with a write lock before calling hu->proto->close() and setting hu->hdev to NULL. The write lock ensures all active readers have completed and no new reader can enter the protocol recv path before resources are freed. This allows the protocol-specific recv functions to remove the "HCI_UART_REGISTERED" guard without risking a null pointer dereference if hci_register_dev() fails.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A race condition in the Linux kernel's Bluetooth HCI UART driver (hci_ldisc) allows incoming UART data to reach the protocol-specific recv handler after resources are freed. When hci_register_dev() fails, the HCI_UART_PROTO_INIT flag is not cleared before calling hu->proto->close() and setting hu->hdev to NULL, allowing freed resources to be accessed.

MitigationApply the kernel patch that adds a write lock to clear HCI_UART_PROTO_INIT before resource cleanup, ensuring all active readers complete and no new reader can enter the protocol recv path.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.4.293, < 5.5>= 5.10.237, < 5.10.258>= 5.15.181, < 5.15.209>= 6.1.135, < 6.1.175>= 6.6.88, < 6.6.141>= 6.12.24, < 6.12.91>= 6.13.12, < 6.14>= 6.14.3, < 6.18.33>= 6.19, < 7.0.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check the running kernel version
    Run 'uname -r' to get the kernel version and compare it to the affected ranges: >= 5.4.293 and < 5.5; >= 5.10.237 and < 5.10.258; >= 5.15.181 and < 5.15.209; >= 6.1.135 and < 6.1.175; >= 6.6.88 and < 6.6.141; >= 6.12.24 and < 6.12.91; >= 6.13.12 and < 6.14; >= 6.14.3 and < 6.18.33; >= 6.19 and < 7.0.10
    Affected if The kernel version falls within any of the listed ranges
  2. Verify Bluetooth subsystem is active
    Run 'lsmod | grep -i bluetooth' or check /proc/bluetooth/ directory exists and contains entries, or run 'hciconfig -a' to list Bluetooth adapters
    Affected if Bluetooth is loaded and active (if not, the driver is not in use and the system is not affected)
  3. Identify if HCI UART driver is in use
    Run 'ls -la /sys/class/bluetooth/' and check if any adapter uses a serial UART connection. Run 'cat /proc/bus/usb/devices' or check 'dmesg | grep -i uart' for UART-based Bluetooth hardware. Also check 'ls /dev/ttyUSB*' or similar serial devices associated with Bluetooth
    Affected if A Bluetooth adapter is connected via UART (HCI UART driver) rather than USB; this driver is only vulnerable when using the UART transport

A system is affected only if it runs a vulnerable kernel version AND uses a Bluetooth adapter connected via the HCI UART (serial) driver, not USB Bluetooth.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.5 / 5.10.258 / 5.15.209 or later
Fixed in 5.55.10.2585.15.209
Interim mitigation

Apply the kernel patch that adds a write lock to clear HCI_UART_PROTO_INIT before resource cleanup, ensuring all active readers complete and no new reader can enter the protocol recv path.

Recommended fix High confidence

Upgrade to one of: Linux kernel 5.5+, 5.10.258+, 5.15.209+, or 6.1.175+ depending on which branch you are on

  1. Identify the currently running Linux kernel version using `uname -r`
  2. Check which affected branch your kernel version falls into (5.4.x, 5.10.x, 5.15.x, or 6.1.x)
  3. For 5.4.x: Upgrade to kernel version 5.5 or later
  4. For 5.10.x: Upgrade to kernel version 5.10.258 or later
  5. For 5.15.x: Upgrade to kernel version 5.15.209 or later
  6. For 6.1.x: Upgrade to kernel version 6.1.175 or later
  7. After upgrade, verify the fix is present by checking the hci_ldisc.c file for the HCI_UART_PROTO_INIT clearing code with write lock, or confirm via vendor security advisory
Caveat Major kernel upgrades (e.g., 5.4 to 5.5) may introduce compatibility issues with custom modules or older drivers; ensure dependent modules are compatible before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-53073 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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